Spark plug tester



Feb. 12, 1935. w BORCHERT ET AL 1,990,772

SPARK PLUG TESTER Filed Jan. 9, 1933 4 Sheets-Sheet 1 III IIIIIIIIN Feb.12, 1935. w BORCHERT ET AL 1,990,772

SPARK PLUG TESTER 4 Sheets-Sheet 2 Filed Jan. 9, 1955 Feb. 12, 1935.

w. BORCHERT ET AL SPARK PLUG TESTER Filed Jan. 9, 1933 4 Sheets-Sheet 5Feb. 12, 1935.

w. BORCHERT El AL 1,990,772

SPARK PLUG TESTER Filed Jan. 9, 1955 4 Sheets-Sheet 4 F T 110 v 11 inthe breaking of the glass of the case.

Patented F eb. 12, 1935 PATENT OFFICE SPARK PLUG TESTER William Borchertand Fred L. Borchert, Rockford, Ill.

Application January 9, 1933, Serial No. 650,774

6 Claims.

This invention relates to testing machines, and more specifically tomechanism for testing the firing capacity of spark plugs.

There has been known heretofore certain mechanisms designed toaccomplish this purpose, but all of them have been open to more or lessserious objection. In some of these machines a single large compressionchamber has been employed having a series of threaded openings eachdesigned to accommodate a different size of plug. In this constructionit was necessary to screw the plug into the threaded opening withSullicient tightness to prevent the escape of gas under the pressureused for testing. This necessitated the use of a wrench which frequentlyslips off the nut, breaking the porcelain of adjacent plugs.Furthermore, the tester is frequently used on the top of a glass showcase, and the use of a heavy wrench in tightening the plugs commonlyresults Another objection to this type of construction lies in the factthat different sizes of holes are required to accommodate the dififerentsizes of spark plugs in common use. This means that it is necessary toplug all of the holes except the one in use, and, consequently, itusually requires the removal of one plug before the plug to be testedcan be inserted. Sometimes it also involves the insertion of a plug in ahole employed for a previous test. This construction also involves thedifficulty in keeping all of the holes air-tight to prevent the loss ofpressure in the compression chamber.

In many of the prior art constructions air has been provided to thecompression chamber from the usual air tanks of garages and the like,the air being supplied under pressure. The objection to this arrangementlies in the fact that it requires a permanent connection between thetesting mechanism and the air line so that the testing mechanism iseither fixed in place or movable only through a relatively small area,depending on whether the connection was made by means of pipes orflexible tubes. Furthermore, since the advent of low pressure tires, theair pressure carried in the usual tanks is too low for satisfactoryoperation of the testing mechanism which requires that the tanks be heldat a considerably higher pressure than would otherwise be desirable.

A primary object of the invention is the provision of a self-containedtesting unit which may be moved from place to place as the occasiondemands, and requires no permanent or fixed connection.

Another object of the invention is to provide wherein handles and plugpositioning mechanism operate in a substantially horizontal plane.

A still further object is the provision of pump. mechanismsuch that thepower required to move the handles is substantially the same throughoutits stroke to provide uniform and smooth operation.

Other objects and attendant advantages will become apparent to thoseskilled in the art from the following description. and the accompanyingdrawings in which-- Figure l is a side view of the tester showing theupper portion in elevation and the base in section;

Fig. 2 is a section on the line 2-2 of Figure 1;

Fig. 3 is a fragmentary top view of the battery holding means and bottompanel;

Fig. 4 is a section on the line 44 of Figure 1;

Fig. 5 is a vertical section, taken longitudinally through the upperportion of the tester;

Fig. 6 is a fragmentary side view of the cradle for holding the sparkplug;

Fig. 7 is a section on. the line 7-7 of Fig. 5;

Fig. 8' is a section on the line 8-8 of Fig. 5;

Fig. 9 is a section on the line 99v of Figure 1;

Fig. 10 is a section substantially on the line 1010- of Figure 1;

Fig. 11. is afragmentary side view of a preferred embodiment of theinvention;

Fig. 12 is a vertical section through the housing of the form shown inFig. 11 showing the contents in elevation, and

Fig. 13' is a'fragmentary View showing the wiring: connections of thepreferred form.

The invention contemplates a. construction having' a compression chamberand pump mechanism for developing air pressure within the compressionchamber. Means are provided for indicating the pressure in the chamber.Likewise, relief mechanism is provided for relieving excessive pressurein the chamber, such as that which might be caused by an explosiontherein; Novel means are provided for inserting the spark plug so thatthe spark gap rests within the compression chamber, and for holding theplug in this position. In order topass a'spark across. the spark gap ofthe plug to testthe same, means are provided for producing such a sparkfrom dry cell batteries. The entire mechanism is so arranged as toconstitute a testing unit, and the glass.

parts are so assembled as to give certain improved and beneficialresults, a portion of which results are obtained solely through thespace relationship of the parts.

Referring first to Figure 1, a housing 11 is ar: ranged to act as a basehaving a hollow interior 12 for the reception and support of electricalmeans presently to be more fully described. Feet '13 are fastened to thebottom side of the housing by means of screws 14, and may advantageouslybe of rubber or other resilient material toprovide a cushion support forthe tester. A body, designated generally by the numeral 15, is securedto the top of the housing 11 by means of screws 16 or by other suitablemeans. In the present instance this consists of a platform 17 having arearwardly extending arm 18 and'an upwardly extending cylinder andchamber portion 19 which are cast'integral in theform of a single piece.Formed inthe body portion 19 is a compression chamber 21 and a cylinder22 connected'by means of a passageway 23 so that air may be passed fromthe cylinder into the compression chamber. A cylinder head 24 ispositioned over the front end of the cylinder 22 by means of cap screws25. The chamber 21 is formed with openings'on both the front and rearside of the portion 19. A bore 26 concentric with and somewhat largerthan the chamber 21 is formed at the forward end of the chamber toreceive an. observation window 27. The window 27 is secured in the bore26 by means of a ring of rubber or other resilient material. This ringconsists of a U-shaped circular piece of rubber having a portion 28arranged to bear against the marginal edge of the window 27 and flangedportions 29 and 31 arranged to bear against the opposed sides of thewindow adjacent its periphery so as to provide a resilient mounting forthe window. A retaining ring 32 is secured against thebody 15 by'meansof screws 33, and'bears against the rubber ring to compress the ringand. hold the window tightly against the body, In this instance we haveshown the window 27 as being of plate glass, but it may be made of anysuitable transparent material, one such material being so-calledshatter-proof or laminated The walls of the chamber 21 are provided withan outlet 34for the threaded reception of a pressure gauge 35 ofconventional design, the

gauge being arranged to indicate the pressure in the chamber andcalibrated to a suitable scale. The chamber 21 is also provided, with anopening 36 arranged for the'threaded reception of a relief valve 37which may advantageously be of the type having a ball valve member 38held in position against a suitable seat by means 'of a spring 39. Thisrelief valve may be made to serve one or a combination of functions,depending upon the desires of the manufacturer. For example, it may beset to open at the predetermined pressure at which the test is to becarried on so that when air is injected into the compression chamber itwill automatically open when the desired pressure is attained and thusautomatically limit the pressure to the testing pressure. Under thesecircumstances, it will be seen that should an explosion occur inthecompression chamber, which might conceivably occurshould a plug beinserted therein covered with gasoline or other explosive fuel, theexcessive pressure thus developed in the chamber would ,be relievedthrough the valve. On the other hand, the pressure gauge 35 may berelied upon solely for the purpose of indicating the testing pressureand n the relief valve set to open at a higher pressure to provide thenecessary safety and thus insure against the eflects of an accidentalexplosion.

The body portion 19 is also provided with a bore 41 at the rear openingof the compression chamberr2l and concentric therewith for the receptionof a gasket 42 of resilient material, prefas to receive the threadedportions of the spark plug within relatively close limits. Thus, throughthis arrangement the conventional spark plug, such as shown at 44 of thetype commonly employed in automotive engines, may be inserted into thecompression chamber with the threaded portion of the plug foremost, asshown in Fig. 5

'until the flange 45 of the plug comes into contact with the bushing 42.The flange is forced against the bushing with sufficient pressure toprevent the escape of air therebetween. In this man- 'ner the spark gap46 of the plug is positioned within the compression chamber so that theperformance of the plug under pressure may be observed through thewindow 27. Since spark plugs for automotive use vary to a certain degreein size, that is, the diameter of the threaded portion of the plug, theinternal diameter of the gasket 42 is made of such size as to closelyreceive the larger of these plugs. In order to prepare the smaller sizesto be similarly tested by 'means of the same devices, a bushing 4'7 isprovided and is threaded on its inner surface for reception on thethreaded portion of the spark size as to bring the threaded portion ofthe smaller plugs to the same apparent diameter as plug, as shown inFig. 8. This bushing is of such the larger plug. It will be seen thatany number of these bushings may be provided to accommodate any smallersize of plug to the testing mechanism. The threads on the inner side ofthe bushing are so made that the bushing may be turned onto and off fromthe plug solely by means of the fingers, so that the testing operationsare not materially retarded by the necessity for using the bushing. Inorder to position a spark plugv with the spark gap in the compressionchamber and the flange firmly against the gasket, a cradle43 is employedhaving a notched upper surface 49 and The forward side of the cradle isprovided with-a face 52 arranged to be brought against the metal portionor nut :53 of the-plug; Thus, when the cradle is moved forward, the

reinforcing 51..

surface 52 of the cradlebears against the nut 53 of the plug forcing theplug into the compres-. sion chamber and the flange 45 firmly againstthe gasket 42. The cradle 48 is pivotally supported through arms 54 and55 to a yoke comprising yoke members 56 and 57, the arms 54 and 55carrying pivots 58 and 59 journaled in the yoke members. The yokemembers 56 and '5'! are in turn journaled at their lower ends on screws61 and 62 in opposite sides of the body 15, and are held together attheir upper ends. by means of a pin 63. The pin 63 also has journaledthereon a latch member 64, the latch member having ears 65 for thereception of the pin .63. 'A coiled spring 66 is wound about the pin 63between the yoke members 56 and 57 and also between the ears of thelatch, and acts between the yoke members and the latch to urge the samein a counter-clockwise direction facing Fig. 5. A shaft 6'7 is journaledin the yoke members 56 and 57 and supports a spur gear 68 fixedlysecured on the shaft between the two yoke members and in a position tobe engaged by the latch member 64. A hand wheel 69 is mounted on theouter end of the shaft 67 to permit manual rotation of the shaft and thespur gear 68. The spur gear 68 is arranged to cooperate with gear teeth'71 on the top of the body portion 19 so that upon rotation of the handwheel 69 the yoke will be rotated about the screws 61 and 62.

Thus, to position the spark plug 44 in a testing position with respectto the compression chamber, the yoke is rotated in a clockwise directionfacing Fig. 5 until it is possible to insert the plug 44 with thefingers into the compression chamber. This will ordinarily necessitatecomplete disengagement of the spur gear 68 and the teeth '71. When theplug is thus positioned, the yoke is rotated in a counter-clockwisedirection and the cradle 48 is guided against the nut 53 of the plug.This operation may be carried out by simply grasping the yoke membersand swinging the yoke. During this movement the spur gear 68 will rideonto the teeth '71. In order to finally tighten theplug into its socket,the operator grasps the hand wheel 69 and rotates it, bringing theflange 45 of the plug snugly against the gasket 42. As the hand wheel isrotated, the latch 64 clicks along the spur gear so that when the handwheel is released the latch prevents backward movement of the gear, thusholding the plug firmly in the tightened position. To release the plug,the latch 64 is moved in a clockwise direction facing Fig. 5, thusreleasing the spur gear in which position the yoke may be rotated to theaforementioned position in which the plug may be removed. The yoke isthus rotatable from an inoperative position in which the plug may beinserted into the compression chamber, and an operative position inwhich the plug is firmly held in its testing position within thechamber.

The piston 72 is positioned in the cylinder 22 for reciprocation tocompress the air in the compression chamber. A leather or other cup 73is positioned at the front end of the piston and is secured thereto bymeans of a nut '74 threaded to a rod 75 on the front end of the piston.The nut 74 is of suflicient width to completely fill the space betweenthe flangesides of the cup and extend slightly beyond these ends so thatwhen the piston reaches the forward end of its stroke, substantially allof the air in the cylinder is displaced. A spring ring '76 acts againstthe flange sides of the cup to maintain them in close proximity to thewalls of the cylinder.

Referring now more particularly to Figs. 9 and 10, the piston isarranged to be reciprocated in the cylinder by means of handles 77 and78. These handles are pivotally supported intermediate their ends on thearm 18 by means of bolts 79 and 81. The handles extend slightly beyondthe pivotal points and terminate in intermeshing gear teeth 82 and 83.Through this arrangement reciprocation of one of the handles bringsabout a corresponding movement of the other handle which insures uniformaction on the piston. The handles are slotted intermediate their ends,as shown at 84 and 85 for the reception of links 86 and 87 whichv arepivotally secured to the handles by means of pins 88 and 89 extendingacross the slots. The forward ends of'the links 86 and 87 are pivotallysupported in a slot 91 in the rear end of the piston 72 by means of athreaded pin 92. The links are curved, as shown at 93, so as to passinto the cylinder to move the piston till the front extremity of thecylinder.

Thus, upon movement of the handles '7 and '78 toward and. away from eachother, the piston '72 is r'eciprocated in the cylinder 22, drawing airinto the cylinder through an opening 94 in the cylinder wall and forcingthe air into the compression chamber 21 through the passageway 23, Avalve is positioned in the passageway 23 and is arranged. to be openedwhen pressure is applied to the end adjacent to the cylind r 22 topermit the passage of air from the cylinder into the compression chamberand to be closed when this pressure is relieved to prevent the returnflow of air. This valve may advantageously be of the type usuallyemployed in automobile tires and commonly called a Schrader valve.

Electrical energy for causing a spark to pass across the spark gap ofthe plug during the testing operations is provided by a secondaryvibratory type induct-ion coil and dry cell batteries positioned in thehousing 11. The induction coil, indicated generally by the numeral 95,is connected to the center conductor 96 of the plug through a lead 97having a spring-operated clip 98 for convenient attachment to the plug.The coil is provided with conventional vibratory mechanism 99 and isprovided with electrical energy from batteries 101, 102, 103 and 104,the flow of :1

occupy their normal position shown in dotted lines in Fig. 9. Novelmeans are employed for holding the batteries and for making the properbattery connections. The coil 95 and batteries are supported upon abottom panel 106 secured to the housing 11 by means of screws 107.Positioned upon the bottom panel 186 are spaced parallel vertical panels108, 109 and 111, the vertical panels being spaced a distance slightlygreater than the diameter of the batteries. A longitudinal panel 112extends between the vertical panels and provides a series of fourchambers for reception of the batteries. A top panel 113 is affixed tothe top end of the panels 108-112, the distance between the top panel113 and the bottom panel 106 being just sufiicient for the reception ofthe battery inclusive of the upstanding central ter-.

minal 114 thereof. Grooves 115 and 116 in bottom panel serve to receivethe upstanding terminals of the batteries 102 and 193 so these batteriesmay only be inserted into their respective chambers with the centralterminal downward. Likewise the upper plate 113 is provided with grooves117 for the reception of the central terminals of the batteries 101 and184 so that these may only be inserted with the terminals on the upperend. This device insures that the batteries will always be inserted inthe proper manner and prevents them from at any time being accidentallyimproperly connected. A spring contact member 118 serves to connect thecentral terminal of the battery 194- with the bottom or outer terminalof the battery 192, while the contact member 119 connects the outerterminal of the battery 103 to the switch 105. Likewise the contactmember 121 connects the central terminal of the battery 101jto theprimary of the coil 95. Likewise spring contact members 122 and 123 onthe bottcm panel 106 serve to connect opposite terminals of thebatteries 101;and 102, and 103 and 104, respectively, to complete thecircuit.

The switch 105 is also connected to ground bymeans of a lead 124 wherebyclosing of the switch tion coil 131 from this source of current.

completes the circuit through the primary of the coil, one lead of theprimary of the coil being grounded by means of a lead 125. In order tofacilitate the insertion and removal of the batteries from their closelyconfined positions, strips of cloth or similar suitable material 126'andv127 are secured to the vertical'panel 109 by means'oi screws 128 and129 and are of sufficient length to loop into adjacent chambers, as'bestshown in Fig. 2. Thus the battery is inserted with the pieces of clothor tabs looped around them so that by pulling the ends of the tabs thebatteries may be slid-cut of their operative positions.

While the means shown in Figs. 1-3, inclusive, for supplying electricalenergy to the plug, under test is of advantage where it is'desired tohave a completely portable testing machine, we have shown inli'igs.11-13 a preferred electrical system, which, while lesscompletelyportable than the form first above mentioned, is suiiiciently portableto normally accomplish'the purpose. In this form a secondary vibratoryinduction coil 131 is secured to'the bottom panel 106 by means of astrap 132, this coil having the usual vibratory elements'133. Oneterminal of the secondary winding of the coil is connected to the sparkplug through the lead 97, the other terminal of the secondary windingbeing grounded. A conventional step-down transformer 134 is also securedto the bottom panel 106 within the housing 11 and is connected with theprimary of the induction coil 131. The transformer 134 is connected to aconventional power receptacle 135 secured in the side of the housing 11,one of the leadsbetween the receptacle and the transformer passingthrough a manually controlled switch 136. Thus, when the receptacle 135is connected to a commercial light circuit such as the'usual or 220 voltcircuits, power will be supplied to the transformer when the switch136.is closed. The

voltage of the commercial power will he stepped down in the transformerto six volts and then supplied to the induction coil 131. a It should beunderstood, of course, that the transformer will vary depending upon thevoltage of the commercial power supply. The primary of the inductioncoil 131 is also connected to terminals 137 and 138 secured in the wallsof the housing 11, the cir-' cuit passing through the switch 105 aspreviously described. The terminals 137 and 138 serve for'the connectionof the conventional six volt storage battery, so that upon the closingof theswitch 105, current will be supplied to the induc- Thus, in thepreferred form just described, the electrical energy may be takenfromeither a conventional storage battery or from a commercial lightingcircuit, depending upon the convenience of these different sources ofenergy. In this manner. the cost of operating the tester will beconsiderably lower than when the same is operated through the use of drycell batteries of the type shown in Figs. 1-3.

The advantage of our improved construction will doubtless have becomeapparent. It will be seen that the device presents a self-contained unitand does not require attachment to a supply of gas or air nor to asupply of electrical energy.

The pressurecin the compression chamberis developed by means of a pumpoperated through horizontally movable handles, the handles beinghorizontally movable in their pumping stroke.

No strain has set up through their operation and, consequently, thedevice may be used on the glass,

showcase of spark plug sales establishments without danger of breakingthe glass during pumping operation. Furthermore, when the handlesaremoved into a parallel position represented by thecompletion of the powerstroke of the piston, the handles occupy a position such as to protectthe switch mechanism from being accidentally actuated. The plug isinserted in the tester entirelywithout' the use of wrenches or otherextraneous positioning means merely through the operation of theyoke, sothat there is no danger of showcases or the porcelains of.

adjacent plugs being broken. Furthermore, the plug is insertedlongitudinally into the chamber and is not screwed min the conventionalmanner which'materially increases the speed with which the test may beconducted, since only an instants time is required for the satisfactoryinsertion of the plug or the removal thereof. Furthermore, all'sizesof'plugs are tested by insertion in the same hole which rendersthemechanism much A novel feature of the invention is the manner 7 ofsupporting and retaining the batteries and the means for removing thesame from their support,'the means being so constructed that thebatteries cannot be inserted in an improper manner.

Attention is also directedtothe fact that we haveprovided means wherebythe electrical energy for operating the tester may be obtained fromeither the conventional six volt storage In the former case theterminals of the battery are conbattery 'or commercial lightingcircuits.

nected directly to the induction coil, whereas when the commerciallighting circuit is employed, the current is firstpassed'through astep-down transformer from which it is supplied to the induction coil atthe desired voltage of six volts.

Independent switch means are provided for use withthe two circuits. 1 1

While we have thus described and illustrated a specific embodiment ofour invention, we are aware that numerous alterations and changes mightbe made'therein without materially departing from the spirit of theinvention and the scope of the appended claims, in which We claim: r

1. In a spark plug tester, a compression chamber having an open end, acompressible gasket positioned in the chamber wall'at said open end, andrack and pinion means for pressing a flange of a spark plug firmlyagainst said gasket'when the threaded end of the plug is inserted insaid chamber to provide a substantially air-tight junction between theflange'and the gasket.

2; In a spark plug tester, the combination of a compression chamberhaving an open end of such diameter as to permit the longitudinalinsertion of the threaded end of a spark plug, a resilient gasketpositioned in the walls of said chamber, means for normally maintainingthe gasket in position, means adapted to bear against the nut of theplug movable toward and away from said open end for inserting and forapplying longitudinal pressure to said spark plug to force the flangethereof firmly against the gasket to provide a substantially air-tightjunction therebetween and a rack and pinion for moving said lastmentioned means for quick insertion of plugs of variable size.

3. In a spark plug tester, the combination of a compression chamberhaving an open end of such diameter as to permit the longitudinalinsertion of the threaded end of a spark plug, a gasket in the walls ofsaid chamber surrounding said opening, cradle mechanism arranged to bearagainst the nut of the plug and a rack and pinion mechanism foractuating the cradle to press the flange thereof firmly against thegasket and provide an air-tight junction therebetween.

4. In a spark plug tester, a compression chamher having an open end on acompressible gasket positioned in the chamber wall at the open end, rackand pinion means for pressing a flange of the spark plug against saidgasket when the threaded end of the plug is inserted in said chamher,and manually operable means for turning the pinion to tighten the plugin position to provide a substantially air-tight junction between theflange and the gasket.

5. The combination in a spark plug tester of a hollow base. carryingelectrical supply means, a compression chamber and a pump chambersupported on the base in superimposed relationship, the compressionchamber having a window defining the front thereof and an opening at therear for the reception of a spark plug, said pump chamber also having arear opening, a piston in the pump chamber, a pair of horizontallydisposed handles positioned on either side of the pump chamber foractuation from the front toward and away from the pump chamber toactuate the piston through the rear opening of the pump chamber, a yokepivoted on the pump chamber spanning the compression chamber forsecuring the spark plug in the opening thereof, and rack and pinionmechanism between the yoke and the top of the compression chamber fortightening and releasing the plug.

6. The combination in a spark plug tester of a hollow base carryingelectrical supply means, a compression chamber and a pump chambersupported on the base in superimposed relationship, the compressionchamber having a window defining the front thereof and an opening at therear for the reception of a spark plug, said pump chamber also having arear opening, a piston in the pump chamber, a pair of horizontallydisposed handles positioned on either side of the pump chamber foractuation from the front toward and away from the pump chamber toactuate the piston through the rear opening of the pump chamber, a yokehaving a pair of arms pivoted on the pump chamber, the yoke spanning thecompression chamber, a cradle connecting the arms and pivotallysupported thereon adapted to contact the nut of a plug to tighten andrelease the plug in the opening of the compression chamber upon pivotalmovement of the yoke, a rack above the compression chamber, and amanually rotatable pinion on the yoke cooperable with the rack for thepurpose of tightening the plug in the compression chamber and releasingthe plug while under pressure. WILLIAM BORCHERT. FRED L. BORCHERT.

